(1) Field of the Invention
The present invention relates to an amplifier capable of reducing the influence of power supply noise, an optical receiver circuit that uses the amplifier, an optical module that uses the amplifier, and a data exchange system that uses the amplifier.
(2) Description of the Related Art
In recent years, the traffic capacity required for a network has increased at an accelerated pace due to recent widespread use of the Internet. In the field of backplane transmission within the housing of a server, router, or other large-capacity data transmission device for a computer, telecommunication apparatus, or the like, it is anticipated that a communication speed of higher than 10 Gbps will be required for signal transmission within the housing of such a large-capacity data transmission device, and that conventional electrical-signal-based communication will be superseded by optical communication, which provides a higher communication speed. For commercialization of optical wiring for optical communication, it is necessary to use a transceiver circuit based on a CMOS process that can be integrated into a logic LSI. As a multichannel capability is essential, it is demanded that a circuit system capable of operating at a high speed with low area requirements be implemented.
Further, as the supply voltage is decreased due to the use of a miniaturized process, the signal level for communication is lowered. Consequently, the influence of power supply noise, which was insignificant in the past, is now nonnegligible. In recent years, therefore, it is also demanded that signal quality be prevented from being degraded by power supply noise.
An optical receiver circuit disclosed in Japanese Patent Application Laid-Open Publication No. 2001-326377 is formed by coupling a photodiode having a light-to-current conversion function to a transimpedance amplifier having a current-to-voltage conversion function in a hybrid manner. The photodiode is directly attached to a circuit board for the transimpedance amplifier by using a hybrid integration method based on wafer bonding. Further, a dedicated electrode pad is mounted on the transimpedance amplifier circuit board to electrically couple the photodiode to the transimpedance amplifier. The transimpedance amplifier is formed by connecting a shunt feedback impedance between the input and output of a circuit that is obtained by serially connecting an odd number of silicon CMOS inverters.
Disclosed in Japanese Patent Application Laid-Open Publication No. S59-115628 is a noise rejection method for use with a receiver that receives a target signal frequency within a frequency band where noise signals extensively exist. The receiver includes a signal receiver unit for tuning in to the target signal frequency and a signal receiver unit for tuning in to a frequency deviated from the target signal frequency and receiving only a noise signal. The output levels of noise signals included in outputs demodulated by the respective receiver units are equalized and set in opposite phase to each other. The noise output signals, which are in opposite phase to each other, then cancel each other to extract a target signal.